Recent years, in order to achieve a weight reduction of a vehicle, a weight reduction of various constituent members of the vehicle have been also challenged. Amongst them, weight reduction of a laminated glass used for a window glass has been also challenged. Here, the laminated glass typically has a configuration in which an interlayer film is sandwiched between two glass plates, and is widely used for various purposes such as the vehicle and a building and the like. The above described weight reduction is also a requirement for the laminated glass for the building as well as the laminated glass for the vehicle.
To reduce the thickness of the glass plate is considered to contribute to the weight reduction of the laminated glass. However, it also causes a large problem that the thinner glass plate necessarily entails a reduced strength of the laminated glass. In addition, it is required for the laminated glass to have a sound insulating property. Nevertheless, there is another problem that the reduced thickness of the glass plate necessarily entails a reduced sound insulating property as well.
To cope with those problems, Patent Reference 1 (JP-B No. 5089497) discloses a multi layered sheet for the interlayer film of the laminated glass that is superior in the strength of the laminated glass, in particular, a better breaking strength, an impact resistance, and a penetration resistance when being fabricated into the laminated glass. When the multi layered sheet disclosed in the Patent Reference 1 is used for the interlayer film, the laminated glass obtained has a rigidity and an improved strength even when the thickness of the glass plate is set thinner. However, there is a problem that the sound insulating property is hardly assured. In the meantime, a certain interlayer film has been known in which the sound insulating property has been improved for the use in the vehicle. In this regard, the laminated glass using this type of interlayer film can assure the sound insulating property even when the thickness of the glass plate is set thinner. However, there is another problem of an insufficient rigidity when a so-called sucking out occurs at a time when the laminated glass is used for a side glass or the like, which is a phenomenon in which the glass is sucked out towards the vehicle exterior due to the vehicle exterior becoming at the negative pressure during the high speed running of the vehicle. For this reason, it is demanded to provide a laminated glass that is capable of having the further higher rigidity and higher sound insulating property while attaining the weight reduction.